This invention relates to a tool for determining axial and angular alignment between a bore and a rod which moves through the bore. More specifically, the invention relates to an alignment tool for a die casting machine to check the axial and angular alignment of the shot sleeve, shot cylinder and shot cylinder rod of the die casting machine.
In the die casting process, molten metal is poured through a side hole into a hollow sleeve called the shot sleeve of the die casting machine. One end of the shot sleeve is connected to a die and the opposite end receives a tight-fitting piston called a plunger for forcing the molten metal into the die. The plunger is connected and actuated by a cylinder rod from a hydraulic cylinder known as the shot cylinder of the die casting machine. The shot sleeve, shot cylinder and shot cylinder rod must be in perfect alignment or the plunger will wear excessively on one side, causing molten metal to leak around it and spray into the surrounding area. Misalignment also wears the shot cylinder rod bearing and the piston within the shot cylinder.
Misalignment can consist of axial misalignment characterized by the longitudinal centerline of the shot sleeve offset from the longitudinal centerline of the hydraulic shot cylinder. In other words, when axial misalignment exists, the axis of the shot sleeve is parallel to the axis of the shot cylinder but the two axes are offset from one another. Misalignment can also consist of angular misalignment characterized by a non-zero angle between the centerline of the shot sleeve and the centerline of the shot cylinder. In other words, when angular misalignment exists, the longitudinal axis of the shot sleeve is not parallel with the longitudinal axis of the shot cylinder. Both types of misalignment, separately or in combination, exist in die casting machines.
Numerous causes for misalignment are known. These include (a) a warped front platen in which the shot sleeve is mounted; (b) an oversized or distorted mounting hole in the front platen for the shot sleeve; (c) the bore in the shot sleeve non-concentric with the outside diameter of the shot sleeve; (d) a warped shot sleeve; (e) a bent shot cylinder rod; (f) a worn cylinder rod bearing; or (g) a distorted die casting machine bed. As with most high precision equipment, repair and replacement of parts is extremely costly.
In order to keep wear to a minimum, proper alignment of the equipment is of great importance and should be regularly checked. Unfortunately, there has been no inexpensive and easily used method of checking alignment. As a result, misalignment in the die casting machine typically goes undetected and uncorrected until it becomes excessive. There remains a need in the industry for a die casting machine alignment tool which can be used regularly, easily and inexpensively to detect axial and angular misalignment of the shot sleeve, shot cylinder and cylinder rod. The primary goal of this invention is to fulfill this need in the industry.
More specifically, an object of the invention is to provide a reliable instrument to measure both axial and angular misalignment and to identify where corrections or adjustments of the die casting machine should be made.
Another object of the invention is to provide an alignment tool of the character described which is economical and can thus be practically used on a regular basis to detect misalignment at an early stage so that adjustments can be made before major repair is required.
An additional object of the invention is to provide an alignment tool of the character described which can be readily understood and utilized by those skilled in the die casting industry.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the description of the drawings.
In summary, the die casting machine alignment tool comprises a tubular connecting sleeve inserted in the shot sleeve and concentrically aligned therewith by tapered cones engaging the ends of the shot sleeve. A rotatable shaft is disposed within the connecting sleeve and carries one or more brackets on the outer ends. Mounted on the bracket is a dial indicator having a work piece engaging spindle to bear on alternative surfaces of the die casting machine such as the die, outside diameter of the shot sleeve, or the cylinder rod to detect and visually indicate any misalignment when the rotatable shaft is rotated within the connecting sleeve.